FLUKA simulation of 15 MeV linear accelerator based thermal neutron source for radiography

Abstract

FLUKA simulation has been carried out using 15 MeV LINAC to design thermal neutron source for radiography. In this case, a neutron collimator has been designed along with e-<img src='/image/spc_char/gamma2.gif' border=0> target, <img src='/image/spc_char/gamma2.gif' border=0>-n target, moderator and shielding. The <img src='/image/spc_char/gamma2.gif' border=0>-n target has been optimized based on their photonuclear reaction threshold. The moderating properties have been studied for a few light elements to optimize best suitable moderator for radiography system. To get best values of collimator parameters such as collimation ratio, gamma content, neuron fluence rate, cadmium ratio, beam uniformity etc., a FLUKA simulation was carried out. The collimator has been optimized with cadmium lining square cone to capture the scattered thermal neutrons and the collimation ratio to L/D=20. The neutron fluence rate and neutron to gamma ratio of the optimized facility at the object plane is 1.1 <img src='/image/spc_char/cross.gif' border=0> 105 n cm-2 s-1 and 1.0 <img src='/image/spc_char/cross.gif' border=0> 105 n cm-2 mR-1.